As most landowners in southeastern Pennsylvania can attest, white-tailed deer represent one of the biggest challenges to managing healthy and ecologically diverse landscapes.
While deer are native to our region, scientists believe that forests evolved to support deer densities of about 10 animals per square mile. But in many parts of southeastern Pennsylvania, populations exceed 100 deer per square mile. This means there simply isn’t enough food for all these hungry deer. In fact, more than 100 species of native wildflowers have gone extinct as a result of deer browse. And many experts believe our forests are being irrevocably changed due to deer consuming nearly all native tree seedlings, eliminating succeeding generations of canopy and accelerating the spread of invasive species that thrive in the added sunlight that makes its way to the forest floor.
Compounding the problem, our warming climate means springtime arrives earlier, fall extends later into winter, and winters are less harsh. The milder temperatures mean more fawns survive to munch their way into adulthood.
Preserve Manager and Wildlife Coordinator Tim Burris is a proponent of a three-fold approach to gardening in “deer country.”
1. Select While it may seem like deer eat everything in sight, certain plants are more likely to be left alone (“deer resistant”). Others can sustain some damage and still survive (“deer tolerant”). Species with a strong fragrance, hairy leaves, or pungent tastes are generally deer resistant.
Also keep in mind that deer appetites are a bit like humans: they have regional preferences. Plant species eaten in one location may be left alone several miles away. Deer browsing habits can also depend on the time of year, alternative food sources and inquisitiveness (deer may nip at a new plant just to see what it is).
2. Protect Tree shelters are photodegradable plastic tubes that protect the vulnerable plants from deer until the trees grow above the “browse line”—the point at which deer can no longer reach to feed on the foliage (usually about five feet).
Repellents can be effective if applied regularly. Don’t buy the gallon jug, but rather alternate repellents since deer get used to a single variety. If you spray frequently, invest in a high-quality sprayer for the best coverage. Natural Lands staff members like back-pack sprayers.
At our Stoneleigh: a natural garden in Villanova, we’re investing in the ultimate protection: an eight-foot-high exclosure fence, which will be installed in June. The openings in the wire fencing sections allow wildlife—other than deer!—to pass through easily. Deer exclosure fences are common practice at most botanical gardens where, like at Stoneleigh, horticulturists are working hard to establish and maintain plant collections, species diversity, and ecological sustainability.
3. Inspect You have invested time, effort and money into your trees and other plants, so don’t walk away now! Inspect them regularly. Check your fencing and repair it, if necessary. Remember to reapply repellents after rain and alternate types.
Diligence is essential if you’re going to give your new plants a chance, especially in areas where deer browse heavily. Your attention will be rewarded with plants that thrive!